Alkylation process



withdrawn as a product of especially high yield and high octane number.In one modiiication of this embodiment the hydrocarbon phase from thefirst alkylation step is freed from hydroiiuoric acid, the organiciiuorine compounds are extracted from the hydrocarbon phase byconcentrated sulfuric acid, and the sulfuric acid extract is used as acatalyst in a second alkylation step wherein an additional amount ofisoparafn is alkylated. In this modication it is particularlyadvantageous to react a tertiary-base olefin with an isoparaiiin in theiirst alkylation step and to react a nontertiary-base olen in the secondalkylation step. In another embodiment of this invention a compositealkylate of especially high octane number is prepared from a mixture ofoleflns by a cooperative combination of steps comprising separating fromthe oleiin mixture a fraction comprising tertiary-base olens, that issubstantially free from nontertiary-base olefins and also a fractioncomprising nontertiary-base oleiins, that is substantially Tree fromtertiary-base oleiins, alkylating a low-boiling isoparalin with theinst-mentioned olen fraction in the presence of hydrofluoric acid as,the catalyst, and separately alkylating a low-boiling isoparaflin withthe second-mentioned oleiin fraction in the presence of sulfuric acid asthe alkylation catalyst.

Various embodiments of this invention will now be discussed withreference to the accompanying drawing, which forms a part of thisspecification and which is a diagrammatic iiow sheet. For the sake ofsimplicity, the discussion will be specifically to reacting isobutyleneand normal butenes with isobutane, although it is to be understood thatthe invention is not necessarily limited to these speciiic hydrocarbons,which are preferred reactants, since the invention may be appliedgenerally to reacting low-boiling oleins with lowboiling isoparaflns,especially olei'ins and isoparains having four to six carbon atoms permolecule,

In one embodiment o this invention, an olencontaining four-carbonhydrocarbon mixture, such as is commonly available in a refinery inwhich cracking processes are conducted, is passed through line i@ toseparating means illustrated by fractionating column Il. Any undesiredlower-boiling hydrocarbons may be removed by fractional distillation andmay be discharged through line l2, and any undesired higher-boilinghydrocarbons may be removed and discharged through line i3.Fractionating means li is operated so as to produce a fractioncontaining isobutylene that is substantially free from normal butenesand a fraction containing normal butenes that is substantially -freefrom isobutylene. When the charge introduced through line ill containsonly a minor proportion of l-butene, such a separation can besatisfactorily effected by fractional distillation. 'Ihe resultantisobutylene fraction is passed through line Ill to 4alkylator I5,wherein concentrated hydrofluoric acid is used as the alkylationcatalyst, and the normal-butene fraction is passed through line IS toalkylator il, wherein concentrated sulfuric acid is used as thealkylation catalyst. However, when the charge in line il) contains asubstantial proportion of l-butene, fractional distillation alone isinadequate, since the lower-boiling fraction will contain l-butene aswell as isobutylene; whereupon these two olens are preferably separatedby passing this fraction from line lll through line 29 to anolen-isomerization step carried out in isomerizer 2i, wherein l-buteneis converted to i 2-butenes. The eiiluent from this isomerization stepis passed through line 22 to separating means illustrated byfractional-distillation column 23. From separation means 23 anisobutylene fraction is passed through line 24% to reactor i5, and anormal-butene fraction is passed through line 25 to reactor Il.

Other means can be employed to eiect a satisfactory separation ofisobutylene from normal butenes. For example, the charge passing throughline lil may be preliminarily subjected to selective polymerization,whereby substantially onlythe isobutylene is polyinerized, leaving thenormal butenes unreacted. A normal-butene fraction substantially yfreefrom isobutylene can be readily separated from the polymerizationeiiiuent, and the polymer can be subjected to depolymerization to formisobutylene, which can be recovered substantially free from normalbutenes. A similar procedure can be applied to the material passingthrough line 23. However, separation by isomerization of the l-butene ispreferred as being most advantageous because of its relative simplicity,economy, and efficacy.

In alkylator i5 the isobutylene is reacted with isobutane in thepresence of liquid hydrouoric acid as alkylation catalyst. Whenisobutane is present in the charge introduced through line i5, theisobutylene fraction passed through line lil contains substantially allof this isobutane. Additional isobutane can be charged from a suitableoutside source to the system through line 25. The effluent fromalkylator i5 is passed through line 2l to separating means 36, whereinit is separated into a liquid hydrofluoric acid phase and a liquidhydrocarbon phase. The hydrofluoric acid phase is recycled through line3| back to alkylator l5; ordinarily a part of it is passed through line32 to purification o1' regeneration means not shown. The hydrocarbonphase is `freed from hydrofluoric acid, preferably by distillation as a10W-boiling mixture with isobutane, and is then passed from separatingmeans 3Q through line 33 to rfurther separating means, illustrated byfractional-distillation column 315i.

Simultaneously with the alkylation in alkylator l5, the normal butenesare reacted with isobutane in alkylator il' in the presence ofconcentrated sulfuric acid as alkylation catalyst. It it generallynecessary to add isobutane from an outside source for this allrylation,as through lines 25 and 2B. The eiiiuent from alkylator il is passedthrough line 35 to separating means 3%, wherein it is separated into asulfuric acid phase and a hydrocarbon phase. The sulfuric acid phase isordinarily recycled at least in part through line 3l to the alkylatoril, and may be discharged in part through line 38. The hydrocarbon phaseis freed from traces of acidic materials, as by an alkaline wash, and isthen passed through line Eil to separating means 313.

In separating means Sli, the eiliuents from the two alkylation steps aretreated as a single hydrocarbon mixture to eiect separation into severalfractions. Undesired low-boiling material is removed through line til,and undesired high-boiling material is removed through line il Alightalkylate fraction is removed as a product of the process throughline 42; it consists of paraiiins boiling within the gasoline range thatwere formed in both of the alkylations, and it has a higher octanenumber than that of a corresponding product from reaction of the mixedolefins charged through line Hi with isobutane under allrylationconditions while still mixed together..

Any normal butane which may be present can be discharged through line43. isobutane fraction is removed through line 44 and is preferablypassed'through-line 45 to alkylator vI'I; it contains a major part ofthe korganic iluorine compounds that pass from separating means 3-0through line 33.

In a modification of this inVention, the hydrocarbon material fromseparating means 30 is passed from line 313 through line 150 directly toalkylator I'I. In consequence, the organic iiuorine compounds aresubjected to reaction in :the presence of sulfuric acid as catalyst toproduce additional hydrocarbons boiling in the gasoline range,concomitantly with the alkylation taking place between normal butenesand isobutane. As will be appreciated by one skilled inthe art,

the hydrocarbon material vpassing through line 5u contains a largeproportion of unreacted isobutane; however, since it is generallydesirable to maintain the ratio of unreacted isobutane to alkylate quitehigh during alkylation, it will gen.- erally be desirable to addadditional isobutane through line 28. v

In a further modification ofl this invention, the hydrocarbon materialis passed from line 50 through line 5I to absorption means 52, whereinit is contacted with concentrated sulfuric acid charged to the systemthrough line 53. This sulfuric acid extracts from the hydrocarbonmaterial organic uorine compounds. The extracted hydrocarbon materialthen passes from absorption means 52 through line 54 to separating means36, and after purification therein it vis passed through lines 39 and 33to separating means 3d. The sulfuric acid, containing absorbed organicfluorine compounds, is passedv from absorption means 52 through line 55-to alkylator Il, wherein it is used as alkylationcatalyst.

In either of ythese two modincations, the unreacted isobutane, passedthrough line 4d, is substantially free from uorine compounds and may, ifdesired, be returned to alkylator I5 through line 58. A.

My invention will generally be applied to an olefin-containing chargestock which contains both isobutylene and normal butenes such as hasbeen described in connection with the charge through line It. However,it will be realized that many of the advantages discussed herein can beobtained when charging stocks are available containing only isobutyleneas the` olefin and only one or more normal butenes as the olen. Suchcharge stocks can be passed to the system through lines' and 51,respectively.

The alkylation conditions which are to be used in alkylator I5 andin-alkylator I'I will not be different from those disclosed in the artin connection with the use of catalysts,V discussed. v The alkylation inalkylator I5 will generally be under a pressure vsuch that the materialswill be present as liquids, with a high ratio of isoparaflin to` olen,with a ratio of catalyst tohydrocarbon between about-0-5zl and 3:1, Aand`a reaction temperature between about 50 and about 125"` F. Theconditions in alkylator uII will be much the same except'that thereaction temperature should generally be lower, such as betweenabout-35'and about 70 F. The olefin isomerization conducted in isomerizer ZIcan be carried-out vin any-manner known to the art. I have found thatparti'cularly advantageous results are obtained .by

contacting the olen material with a chromium Y y is no appreciabledehydrogenation of olefin matef rial. The sulfuric acid extractionconductedin absorption means 52 ,is conducted at. a temperature betweenabout 35 and about 100 F.,l with.

vlikewhich can be readily designedand supplied by one skilled in the artin the light of the present discussion. Y

My invention is further illustrated by .the following examples, whichshould not be so construed as to limit the invention unduly.

Example I A refinery fraction containing approximately equimolecular.proportions of isobutylene and of each of the normal butenes isfractionally distilled to separate 2-butene 'as a kettle fraction. Theoverhead: fraction is subjected to isomerization by a catalyst,preferably a catalyst comprising chiefly one or more oxides of the groupof metals consisting of aluminum, beryllium, chromium, and magnesium,further preferably black chromium oxide, to isomerize about-threefourths of the l-butene to Z-butene. v The isomerization eiiiuent isfractionally distilled to separate the Z-butene from theisobutylene :andunisomerized l-butene. The isobutylene fraction, which now contains onlya relatively minor proportion of 1-butene, may beV passed to ahydrofluoric acid alkylation step, but it usually Yis preferably rstsubjected to a second stage of isomerization and fractionaldistillation, whereby; the content of l-butene is further decreased.HThe isobutylene fraction is then used for the yalkylation of isobutanein the `presence of hydroiiuoric acid under alkylation conditions, andthe composite of 2 butene fractions issimilarly used in a step for thealkylation of isobutane in the presence of sulfuric acid under separatesuitable alkylation conditions. The alkylation eiiiuen'ts are separatedinto hydrocarbon and catalyst phases in separate settling tanks. Thehydrocarbon phase from the hydrouoric acid alkylation is freed fromdissolved hydrofluoric acid by distillation of the acid as a low-boilingmixture with Visoblitane, which is recycled to the alkylation step; itis freed from vorganic iluorne-byv contact under deiluoriN nationconditions with granular bauxite or similar defluorinating contactmaterial.' The hydrocarbon phase from the sulfuric acid alkylation isfreed from traces of acidic materials by washing with an alkali. Thethus purified hydrocarbon phases are combined and are subjected tofractional distillation to isolatethe motor-fuel fraction, which isobtained in exceptionally high yield and is of exceptionally high octanerating, being notably superior in these-respects `tothe product obtainedby use oi' the original mixture of butylenes as suchfor alkylation. ofisobutane inthe presence of` either hydroiiuor-icy acid ,or ysulfuricacid. The exact magnitude of the advantage of this invention withrespect to yield and octane rating depends somewhat on the exactcomposition of the originalmi-xture of butenes .and on 'the extent ofisomerization of labuteneto 2-.butene,

but. generally the,.yieldisgreaterhby several .per

cent, and theioctane number of the motor-'fuel product is greater byabout 2 A. 'I'. M. 'ctane number units.

The following typical numerical data for continuous pilot-planecatalytic alkylation .of isobutane with various butenes illustratesuitable stantially free Yfrom normal butenes and a trace tioncomprising a normal butene and substantially free from isobutene,reacting said isobutene fraction with isobutane under alkylationreaction conditions and in the presence of concentrated alkylatingconditions, and also demonstrate that b hydrofluoric acid as thealkylation catalyst, sepoptimum yields and octane ratings areobtainedarating a hydrocarbon phase from efliuents of when isobutylene is usedWith hydrofluoric acid said alkylation containing unreacted isobutane,as the catalyst and When normal butenes are used products of saidalkylation and a minor amount With sulfuric acid as the catalyst,whereas mix- 10 of organic luorine compounds produced during tures ofisobutylene and normal butenes yield and incidental to said alkylation,reacting said relatively inferior results With either catalyst.hydrocarbon phase with said normal butene frac oatuyst HF HF HF HF H2801H2804 H280. H2801 H2804 Rcactants, weight per cent: Y

Isobutylene 7. 9 0 0 9. 4 0 0 9.1 12. 0 o 0 9.7 7.1 0 16.5 o o 0 9.6 0 08.7 16.2 0 0 82.9 90.4 90.1 88.5 68.6 83.8 88.5 90.9 88.0 0 0 0.2 0 21.40 0 9 0 0 0 0 0 1.3 0 0 0 0 10.5 9.0 9.1 4.9 7.6 5.9 4.9 9.6 7.1 0.770.67 0. 77 0.62 1 0.7 1 0.9 0.7 82 114 116 116 50 50 50 50 6s 14.5 9.211.6 7.0 2s 20 25 25 10 Total alkylate:

Yield, Weight per cent of butene 201 196 200 185 1941 200 195 184 180Composition, volume per cent' Bening 8.2 13.9 13.0 12.4 10 11 12 18 19Boiling 203-260 86.5 77.8 76.2 73.5 85 81 79 73 66 B6i1mg260 F 5.3 8.810.8 14.1 5 8 9 14 18 Light alkylate:

ounpomt, F 365 378 888 665 302 302 350 357 302 Yield, volume per cent.99.1 96.3 98.2 96.1 95.8 93 96 90 81 octane No. (ASTM) 95.6 92.8 89.290.6 94.0 94.0 92.5 90.5 91.5

Example II tion under alkylation reaction conditions and in Isobutane isalkylated with an isobutylene fracgli; ea g1 cnrgvyfurg C12 e tion undereconomically favorable conditions in n. .y mg. om

. of the last said reaction a low-boiling, noimally the presence ofhydrofluoric acid 1n a rst alkylan 1 L.

l1qu1d, pai anime hydi ocarbon fraction containing t1on step. Thealkylatmn reaction m1xture 1s paraffin hyd1ocarbons produced 1n eachsa1d alseparated into hydrocarbon and catalyst liquid kylaton 1 e actionbss 'rld rfellllygog palfs firecis 2. An improved process for producingl0vv-boil 13.15110 Vh i; ldo o b ha y .a therps ed t a 40 ing normallyliquid parain hydrocarbons from a lo 1i lytfocas on? Wslll t i I; s. gbmixture comprising isobutene and a normal bu- *ecldta 'kaltl epdm Cm1-cl alnrsblg tene, which comprises separating from such a Je@ t. o a' tf1.fm un Il icon? labyt n of ac mixture a fraction comprising isobutene andsub- ,fm 1 1%n-s trs lmw f ro m t* l elfr ri' 4r) stantially free fromnormal butenes and a fraclqanddtl. elprertlce O C ngen a et su u 1C tioncomprising a normal butene and substantial- ?C da 210,11? 1551,11 ane myai tfa'n agteousty ly free from isobutene, reacting said isobutene m 1rotu@ m obl 1s ts.econ ab 52a lo? si ep 0 fraction with isobutane underalkylation reaction mam 1mg favora e @130s/cof 15% u Igel mcg conditionsand in the presence of concentrated 11g-1g lotef n and tf ISOPSM@ o a yated te 50 hydrofluoric acid as the alkylation catalyst, seplai zy a ionreac ion tnlnx ulre l spara e llho arating a hydrocarbon phase fromeiuents of said ydrocalbon and Caf a yst lqm p ases. and e alkylation,reacting said normal butene fraction hydrocarbon phase is'passed 'to afractlonatOI 1n with isobutane under alkylation reaction condi- Which 1t1s separated into deslred fractions, commons and in the presence ofConcentrated su1 prsmg (l) unreacted lsfbutane Whfch 1S re' r uric acidas the alkylation catalyst, separating cycled, together with a minorprOpO'ltlOn 0f hy- 5" a hydrocarbon phase from eiiiuents of saidalkyldrouoric acid, to the second alkylation step, (2) ation Combiningthe two Said hydrocarbon normal lontane, Wlfllch 1S removed from thePTOCSSS phases and fractionallly distilling the resultant fordehydrogenation, 1f desired, to normal butylmixture in a commonfractional distillation sysenes that'may be fed to the second alkyltlntem, removing from said distillation system as a Step, (3) n10 01`fllfl, Whln 1S Wlthdlawn as a e0 product of the process alow-boilingnormally liq- PIOdlJ-Ct 0f h lgn Yle 1d and Quanti?, and (4) a uidparaflnc hydrocarbon fraction containing heavier fraction which 1sWithdrawn as a byparaflin hydrocarbons produced in both said alp'OQ-UC-kylations, removing also from said distillation Smce thlS invention maybe practlced otnrsystem a fraction comprising unreacted isobu- WlSe thanas SDBClCaly deSCIlbed. and Since tane, and containing a minor amount oforganic many Variations OI TnOdflCatOnS 0f it W111 be iluorine compoundsformed during and incidental obvious to the skilled in the art, itshould be to the nrst said alkylaticn, and passing said fraclmted Onlyin ECCOIdJnGG With the appended tion solely to the second saidalkylation. claims. 70 3. An improved process for producing low-boil- Iclaim: n ing normally liquid parailin hydrocarbons from a 1. An improvedprocess for producing 10W-1OO11-V mixture comprising isobutene and anormal buing nOlInally liquid DaIaffln hydrocarbons from tene, whichcomprises separating from such a a mixture comprising isobutene and anormal mixture a fraction comprising isobutene and subbutene, Whichcomprises separating from such a stantially free from normal butenes anda frac- ;mixture a fraction comprising isobutene and subtion comprisinga normal butene and substantially free from isobutene, reacting saidisobutene fraction with isobutane under alkylation reaction conditionsand in the presence of concentrated hydrofluoric acid as the alkylationcatalyst, separating from effluents of said alkylation a fractioncomprising unreacted isobutane and a minor amount of organic fluorinecompounds produced during and incidental to said alkylation, andreacting said isobutane fraction and the aforesaid normal butenefraction under alkylation reaction conditions and in the presence ofconcentrated sulfuric acid as the alkylation catalyst, and recoveringfrom effluents of each said reaction higherboiling para'ns so produced.

4. An alkylation process which comprises reacting a low-boilingisoparafn and a low-boiling tertiary-base olefin under alkylationreaction conditions and in the presence of concentrated hydroluoric acidas the alkylation catalyst to produce higher-boiling paraffinhydrocarbons, separating from eflluents of said reaction a fractioncomprising unreacted low-boiling isoparafn and a minor amount of organicfluorine compounds produced during and incidental to said reaction, andreacting said fraction with a low-boiling nontertiary-base olefin underalkylation reaction conditions and in the presence of concentratedsulfuric acid as the alkylation catalyst to produce higher-boilingparaflin hydrocarbons and remove organic fluorine compounds, andrecovering from eiiluents of each said reaction higherboiling paraiiinsso produced.

5. The process of claim 4 in which said isoparain is isobutane, saidtertiary-base olen is isobutene, and said normal olefin is a normalbutene.

6. A process for producing low-boiling normally liquid parafnhydrocarbons from a mixture comprising a low-boiling tertiary-base olenand a low-boiling non-tertia-ry-base olen, which comprises separatingfrom such a mixture a fraction. comprising a low-boiling tertiarybaseolen and substantially free from non-tertiary-base olens and a fractioncomprising a non-tertiary-base olefin and substantially free fromtertiary-base olefins, reacting said tertiarybase olen fraction with alow-boiling isoparaffin under alkylation reaction conditions and in thepresence of concentrated hydroluoric acid as the alkylation catalyst,separating a hydrocarbon phase from eluents of said alkylation, reactingsaid non-tertiary-base olefin fraction with a low-boiling isoparaflinunder alkylation reaction conditions and in the presence of concentratedsulfuric acid as the alkylation catalyst, separating a hydrocarbon phasefrom eiiiuents of said alkylation, combining the two said hydrocarbonphases and fractionally distilling the resultant mixture in a commonfractional distillation system, removing from said distillation systemas a product of the process a lowboiling normally liquid parafnichydrocarbon fraction containing paraffin hydrocarbons produced in bothsaid alkylations, removing also from said distillation system a fractioncomprising unreacted low-boiling isoparafiin, and containing a minoramount of organic iiuorine compounds formed during and incidental to thefirst said alkylation, and passing said fraction solely to the secondsaid alkylation.

7. An improved process for producing lowboiling normally liquid parafnhydrocarbons from a mixture comprising isobutene and a normal butene,which comprises separating from such a. mixture a fraction comprisingisobutene and substantially free from normal butenes and a fractioncomprising a normal butene and substantially free from isobutene,reacting said isobutene fraction with isobutane under alkylationreaction conditions and in the presence of concentrated hydrouoric acidas the alkylation catalyst, separating a hydrocarbon phase from eluentsof said alkylation, passing said hydrocarbon phase to an absorptionmeans and contacting same Iwith concentrated sulfuric acid to absorborganic iluorine compounds, separating from said absorption means ahydrocarbon phase and a sulfuric acid extract, reacting said normalbutene fraction with isobutane under alkylation reaction conditions andin the presence of a concentrated sulfuric acid alkylation catalystcomprising said sulfuric acid extract, separating a hydrocarbon phasefrom effluents of said lastmentioned alkylation, combining the last saidhydrocarbon phase and the hydrocarbon phase from said absorption meansand separating from the resultant mixture as a product of the process alow-boiling normally liquid paraiiinic hydrocarbon fraction containingparaffin hydrocarbons produced in both said alkylations.

8. An alkylation process which comprises reacting a low-boilingisoparaln and a low-boiling tertiary-base olefin under alkylationreaction conditions and in the presence of concentrated hydrouoric acidas the alkylation catalyst to produce higher-boiling paraiinhydrocarbons, separating a first hydrocarbon phase from effluents ofsaid alkylation, passing said hydrocarbon phase to an absorption meansand contacting same with concentrated sulfuric acid to extract therefromorganic iiuorine compounds contained therein, separating from saidabsorption means a second hydrocarbon phase and a sulfuric acid extractphase, reacting a low-boiling isoparafln and a low-boilingnon-tertiarybase olefin under alkylation conditions in the presence of aconcentrated sulfuric acid alkyla.. tion catalyst comprising theaforesaid sulfuric acid extract'phase as the alkylation catalyst toproduce higher-boiling paraffin hydrocarbons, separating a thirdhydrocarbon phase from effluents of said last-mentioned alkylation, andseparating from said second and third hydrocarbon phases normally liquidparaiiinic hydrocarbons of motor fuel boiling range so produced.

9. The process of claim 1 wherein said lastnamed reaction is conductedat a temperature of from 35 to 70 F.

10. The process of claim 7 wherein said step of contacting saidhydrocarbon phase with concentrated sulfuric acid to absorb organicuorine compounds is conducted at a temperature of from 35 to 100 F. witha volume ratio of acid to hydrocarbon between about 0.5:1 and 3:1.MARYAN P. MATUSZAK.

REFERENCES CITED The following references are of record in the iile ofthis patent:

UNITED STATES PATENTS Number Name Date 2,267,730 Grosse et al Dec.,30,1941 2,335,507 Grosse et al Nov. 30, 1943 2,327,926 Oakley et al Aug.24, 1943 2,348,017 Miller May 2, 1944 2,373,101 Clarke Apr. 10, 19452,330,206 Dryer et al Sept. 28, 1943

